Quiet repeat-line-indexing mechanism

ABSTRACT

In a typewriter in which a frame-based power mechanism is responsive to a carriage return key to operate a carriagesupported line-indexing mechanism and then to draw the carriage in return direction by a limitedly movable cushioning counterstop means, provision is made so that then the said power mechanism under key control will intermittently effect line indexing operations and furthermore said counterstop means during said intermittent operations is blocked against movement to prevent carriage movement.

United States Patent [72] Inventor Robert E. McGrath 102 West St., Rocky Hill, Conn. 06067 [21] Appl. No. 28,265 [22] Filed Apr. 20, 1970 [45] Patented Dec. 7, 1971 Continuation of application Ser. No. 690,488, Dec. 14, 1967, now abandoned. This application Apr. 20, 1970, Ser. No. 28,265

[54] QUIET REPEAT-LlNE-INDEXING MECHANISM 6 Claims, 5 Drawing Figs.

[52] US. Cl. 197/65, 197/120 [51] Int. Cl B41] l9/70 [50] Field 01 Search 197/l20, 65

[56] Relerences Cited UNITED STATES PATENTS 1,931,383 10/1933 Hart v l97/66 Helmond 197/120 X 2,395,763 2/1946 Sagner 197/120 X 2,567,937 9/1951 Hart 197/66 3,208,575 9/1965 Emig 197/120 X 3,263,793 8/1966 Brignole 197/120 3,276,561 10/1966 Berg 197/120 X Primary Examiner- Edgar S. Burr Attorneys-Joseph R. Spalla and Cornelius P. Quinn ABSTRACT: In a typewriter in which a frame-based power mechanism is responsive to a carriage return key to operate a carriage-supported line-indexing mechanism and then to draw the carriage in return direction by a limitedly movable cushioning counterstop means, provision is made so that then the said power mechanism under key control will intermittently effect line indexing operations and furthermore said counterstop means during said intermittent operations is blocked against movement to prevent carriage movement.

PATENTED DEC '1 197i 33525; 332

sum 1 or 2 INVENTOR ROBERT E. McGRATH BY (LN/w; W

ATTORNEY BACKGROUND OF THE INVENTION This invention relates to electric typewriters and more particularly to a carriage movement-limiting stop which greatly reduces carriage jog and noise arising from carriage movement incident to repeat operation of a carriage return key to effect line spacing or platen indexing.

In modern electric typewriters having a movablecarriage and a carriage return drawband, carriage drawband has one end connected to a platen-indexing lever mounted on the carriage and when a carriage return key is depressed, a clutch on the stationary portion of the machine becomes closed and held by a latch to couple a power source to wind the carriage return drawband. The pull resultingly exerted on the carriage drawband effects first an operation of the line space or platenindexing device and then returns the carriage until the carriage return margin stop engages and displaces a movable counter stop to a limit position on the carriage. A margin control bellcrank or knock-off lever is in the operating path of said counter stop and becomes operated thereby to trip the clutch latch to decouple the power source and thus the pull on the carriage return drawband is ten'ninated so that the platenindexing lever is allowed to return to its normal position. Whenever it is frequently desirable to effect repeat platen indexing, the carriage return key is manipulated to cause the indexing device to produce the desired number of spaces.

A particular disadvantage in known machines, however, is that if the carriage return key is operated to cause additional platen-indexing operations, the clutch must repeatedly be operated, that is the margin stop on the carriage following each action of the drawband must move and operate the counter stop in order to release the clutch-following platen indexing. This is so even though the carriage, following the carriage return operation is already in the correct left margin position. Thus, whenever the carriage return key is manipulated to effect repeat line spacing or indexing, the carriage repeatedly jogs in order to operate repeatedly the counterstop. This results in objectionable noise, vibration, unnecessary wear of parts and occasionally in damage to the carriage return mechanism.

SUMMARY In accordance with the invention, provision is made so that if the carriage return key is operated and held operated for causing repeat platen indexing, the carriage return clutch latch will become disabled after the carriage becomes returned to a left margin position. Furthermore, in accordance with the invention the platen clutch is intermittently closed repeatedly until the carriage return key is released. For this reason, after the carriage is returned and settled in a left margin position, there is no necessity incident to platen-indexing operation for moving the carriage in return direction to operate the counter stop to unlatch the clutch. The invention provides a single element which when the carriage after being returned settles to a left margin position serves to disable the carriage return clutch latch and provides automatically for the activation of a stop or blocking means which will limit the counterstop so as to preclude carriage movement while the carriage return key is held operated for repeat platen indexing. Following the release of the carriage return key, any started indexing operation will be completed and the latch for the clutch control member becomes automatically released just as soon as the carriage thereafter is moved from the margin position.

It is an object of the present invention to provide means for preventing the latching of a carriage return control member in closed clutch position whenever the carriage is moved to or becomes stationed in a left hand margin position.

It is also an object of the present invention to greatly minimize or prevent carriage movement during repeat line indexing operations of the platen, namely to block the carriage in its left margin position against return travel by providing a carriage return movement-limiting stop which becomes active automatically when the carriage after its return assumes its line start position.

Other objects and advantages of the present invention will become apparent from the following description, the claims and the accompanying drawings which disclose by way of example the principles of the invention and a preferred embodiment thereof.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a side elevation view of a conventional key and clutch trigger mechanism for platen-indexing and carriage return operations;

FIG. 2 is a perspective view of a clutch control mechanism for effecting platen indexing and carriage return through a carriage return drawband;

FIG. 3 is a rear view of a portion of a typewriter illustrating in a normal position a margin control counterstop means and further a blocking means therefor in a normal ineffective position;

FIG. 4 is a rear view of a portion of a typewriter illustrating the counterstop means and the blocking means of FIG. 3, with the counterstop means having been moved by the carriage return margin stop to a limit;

FIG. 5 is a rear view of a portion of a typewriter illustrating the carriage dropped back from intercepted position and with the blocking means in position to block the counterstop means and the carriage against return movement.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown in FIGS. 1 and 2, a carriage return key 2 operable to initiate in turn, a platen-indexing and carriage return operation. More particularly, as viewed in FIG. 1, the carriage return key 2, pivotally mounted at one end to pivot about a rod 3 fixed to the typewriter frame. This key, when operated actuates a sublever 4 pivotally mounted on a rod 5 fixed to the typewriter frame. A link 6 attached to the upper portion of sublever 4 interconnects sublever 4 with an upper portion of a trip arm 8 for a wrap spring clutch l8. Said trip arm 8 is pivotally mounted at its lower end about a support 10 fixed to the typewriter frame. Stops 7 and 9 fixed to the typewriter frame serve respectively to limit for clockwise movement of carriage return key lever 2 about stud 3 and a limit for clockwise movement of sublever 4 about stud 5.

A pair of lugs or cars 14 and 15 formed on trip arm 8 function as a primary ans secondary clutch-opening stop respectively, for an ear l6 projecting from one end of a wrap spring clutch l8 normally loosely on a continuously rotating shaft 22, said ear 16 being adjacent to said trip arm 8 and normally contacting the clutch-opening stop 14 thereon, see FIG. 1. The other end of the wrap spring clutch 18 has anchorage in a boss 19 on the cam member 20 and is normally stationary therewith. A spring 12 connecting the upper portion of trip arm 8 to the typewriter frame biases trip lever 8 in a clockwise direction to the normal position seen in FIG. 1. The shaft 22 normally rotates idly within the cam member and its bosses l9 and 20.

The cam 20 has associated with it a cam follower lever 24, pivotally mounted at its bottom end on support 10 in juxtaposition with the trip arm 8. A spring 28 connects an upper portion 30 of the follower lever 24 to the typewriter frame, biasing the follower lever 24 against the periphery of cam member 20.

A normally open carriage return clutch, generally indicated by numeral 44, when operated couples the drive of the rotating shaft 22 to a drum 48 which is rotatably mounted on the shaft 22 adjacent a shoulder on the shaft (not shown). The carriage return clutch 44 includes a clutch face on the drum 48, a yieldable disc member 45 fixed to the shaft 22 and rotating therewith adjacent the face of drum 48, and a disc 46 mounted for relative axial movement along shaft 22 and adapted to move the yielded disc member 45 into clutched engagement with the face of drum 48 so as to cause drum 48 to rotate and wind a carriage drawband 50 thereon.

A bellcrank 34, lying in a plane perpendicular to a plane in which lever 24 is swingable is pivotally mounted about a stud 36 fixed on the typewriter frame. The bellcrank 34 has an open slot 39 formed therein whereby it is communicative with a stud 38 protruding from a portion 41 of a clutch control arm 40 that extends inwardly over the drum 48 and has an arm 32 extending into the clockwise-operating path of upwardly extending portion 30 of arm 24 so as to be operable thereby to operate control am 40 to closed clutch position counterclockwise in response to clockwise movement of arm 24.

A clutch latch member 54 lying in a plane parallel to that of bellcrank 34, slightly thereabove is pivotally supported on a stud 56 formed on the typewriter frame and includes an arm 55 overlying a rearwardly extending arm 60 of hell crank 34. The crank 34 has formed on rearwardly extending arm 60 an upstanding ear 58 whereby it becomes held in closed clutch position by a shoulder 64 of a clutch latch member 54 whenever it is moved to such position. A spring 62 connected between the arm 32 of bell crank 34 and clutch latch member 54 normally biases clutch latch member 54 counterclockwise against upstanding ear 58 so that if the bellcrank 34 is moved counterclockwise to closed clutch position the shoulder 64 of the clutch latch member 64 will hold bellcrank 34 in a such counterclockwise position. In order to unlatch bellcrank 34 the latch member 54 has a link 66 associated with it in a longitudinal slot 68 and the other end of the link 66 extends pivotally from an operating lever 110 pivotally mounted on a stud 112 formed on the typewriter frame. Operating lever 110 is adapted to pivot about stud 112 for moving the end 67 of link 66 from the right end of the longitudinal slot 68 to engage the other end and swing the latch member 54 free of the ear 58. A spring 111 connecting an end of operating lever 110 to the typewriter frame biases operating lever 110 in a clockwise direction and thereby positions normally the end 67 of link 66 normally away from the left end of longitudinal slot 68 so that the spring 62 is able to move the latch member 54 to hold the ear 58 when the clutch-closing crank 34 is operated counterclockwise.

The carriage drawband 50, connected at one end to drum 48, extends from the drum and is trained first around pulleys (not shown) mounted on the typewriter frame, then as shown in FIG. 3, around a pulley 77 carried by the carriage 78 and finally is connected to an indexing lever generally indicated at 81, pivotally mounted on a shaft 83 carrying a platen 87. Indexing lever 81 carries a pawl 52 engageable with a ratchet 71 wheel-carried fast on the platen shaft 83.

As shown in FIG. 3, the movable carriage 78 carries an adjustable left margin stop 76 with a depending shoulder 80 for engaging a counterstop member 82 which is limitedly movable on the frame. The counterstop member has elongate apertures 88 and 90 formed therein which cooperate with studs 84, 86 supported on a frame supported bracket 81 to give it capacity for sliding movement in return direction. Such sliding movement is limited by a bent ear 85 on a frame-supported bracket 81 so that the return movement of the carriage 78 becomes stopped by the counter stop member 82.

A rearwardly projecting ear 92 formed on the counter stop member 82 is arranged to engage and pivot a margin control bell crank 96 counterclockwise about a stud 98 on the frame by engaging thereon an upreaching arm 94, to release bellcrank 34 from clutch latch member 54 for disengaging the clutch 44 and disconnecting power drive to the carriage return drawband 50 as the counterstop member 82 reaches its limit of operation against the stop 85. A spring 102 connecting the lower arm of margin control bellcrank 96 to the typewriter frame, biases the margin control bellcrank 96 clockwise so that it is normally against a stop 100 formed on the typewriter frame. Arm 94 of the margin control bellcrank 96 has a leftwardly projecting finger 104 having an upwardly extending shoulder 105. Also it has a smaller leftwardly projecting finger 106 below finger 104. Leftwardly projecting finger 104 is adapted to engage an escapement mechanism (not shown) to place the carriage in control thereof and leftwardly projecting finger 106 is adapted to engage a bent out portion 108 of operating lever 110 when margin control bellcrank 96 becomes actuated counterclockwise, thereby to effect the release of bellcrank 34 from clutch latch member 54 and disengage carriage return clutch 44.

In operation, when carriage return key 2 is depressed to a resilient stop 11 underlying it, the sublever 4 pivots counterclockwise pulling link 6 connected to trip arm 8. The pull of link 6 pivots trip arm 8 counterclockwise about support 10 against the biasing action of spring 12. This counterclockwise movement of trip arm 8 about support stud 10 removes primary stop 14 from the ear 16 of wrap spring 18, and at the same time the secondary stop 15 is placed in the path of the spring car 16. Consequently, the wrap spring 18 wraps around and engages the rotating shaft 22 to rotate cam 20 counterclockwise nearly one revolution after which the extending ear 16 of wrap spring 18 engages the secondary stop 15 and thus opens the clutch constituted by the wrap spring 18.

When carriage return key 2 is released allowing sublever 8 to return to its normal clockwise position under the urge of spring 12, the primary stop 14 and the secondary stop 15 are respectively moved into and out of the path of the car 16 of wrap spring clutch 18 so that the latter causes the completion of the revolution of the cam 20 and stops the same.

For every revolution of cam 20, lever 24 acts on the bell crank 34 to swing it counterclockwise about stud 36 where it may become latched by clutch latch member 54. The counterclockwise pivoting of bellcrank 34 exerts an inward pull on stud 38, pivoting clutch control arm 40 counterclockwise about pin 42, thereby engaging carriage return clutch 44 by efiecting axial movement of disc 46 against yieldable disc 45 and drum 48 and causing drum 48 to wind the carriage drawband 50 thereon. The pull of the carriage drawband 50 on indexing lever 81, pivots it to rock the indexing pawl 52 so as to rotate ratchet 71 and platen 87 a predetermined number of spaces, and then moves the carriage 78 until the shoulder 80 on the margin stop 76 engages and moves the counter stop 82 to its limit afforded by the abutment 85, as illustrated in FIG. 4.

The margin counter stop 82 in being moved toward the limit of the abutment 85 engages early by it its projecting ear 92 the upreaching arm 94 of margin control bellcrank 96, pivoting the latter counterclockwise about stud 98 against the biasing of spring 102. As a result of the counterclockwise movement of margin control bellcrank 96, the leftwardly projecting finger 106 engages bent out portion 108 of operating lever 110, operating it pivotally counterclockwise about the stud 112. In being so operated, the operating lever 110 pulls the link 66 so that its end 67 actuates the latch member 54 clockwise about a stud 56, so that the ear 58 of the bellcrank 34 moves free of the latch shoulder 64 and the bellcrank 34 moves clockwise about the stud 36 under the urge of the spring 62 to the position seen in FIG. 2. In turn the bellcrank 34 transmits motion to the control arm 40 of the carriage return clutch 44 to open it, so that now the drawband 50 is only under the tension of a usual weak spiral spring (not shown) associated with the drum 48 and allows the indexing lever 81 to return to its normal position.

After the counter stop member 82 strikes the abutment and the carriage return clutch 44 consequently has opened, the carriage under control of a usual escapement (not shown) advances a usual distance under the tension of a usual carriage feed spring and drawband (not shown) to assume the margin position which the position of the margin stop 76 represents.

From the foregoing it is seen that if the carriage return key is operated to contact but not to fiex the resilient stop 11, there will ensue a power-operated platen-indexing operation followed by a carriage return under the shutoff control of the margin stop 78. The invention provides mechanism whereby the machine can be controlled to produce additional poweroperated platen-indexing operations following the just stated combined platen-indexing and carriage-retuming operation. Such additional platen indexing operations can be caused by operating the carriage return key 2 to an extra extent which will flex the stop 11. Such extra extent operation may be made before or after the combined platen-indexing and carriage return operation has occurred. The duration of operation controls the number of line-indexing operations obtained. If the key 2 is depressed only to the limit of the stop 11, there will be only one line-indexing operation for each key operation. If the key 2 is operated so as to flex the stop 11, the lever 8 is moved counterclockwise to a position in which the ear 16 of the wrap spring 18 clears not only the primary stop 14 but also clears the secondary stop 15 so that the wrap spring clutch wraps and turns with the rotating shaft 22 until after the release of the key 2 the car 16 of the clutch is intercepted by the primary stop 14 of the lever 8. By judiciously controlling the release of the key 2 the wrap spring clutch can be controlled to rotate the cam for as many revolutions as line indexing operations are desired.

With the present invention, a device is incorporated which prevents the latch 54 from holding the carriage return clutch in closed position while the carriage is in the line start position. This, as will become clear later herein, eliminates the necessity of carriage movement to unlatch the carriage return clutch at the end of each platen indexing operation.

As shown in FIG. 3, a latch or blocking means 116 is contiguous to the margin control bellcrank 96 and pivotally mounted on a stationary stud 118 formed on the typewriter frame. A rearwardly extending ear 122 is formed on latch 116 or blocking means and extends through a plane in which the margin control bellcrank 96 is movable and is capable of contact with a shoulder 105.

A cam surface 124 on latch 116 is provided below ear 122 for camming engagement with bent out ear 108 of lever 110. Latch 116 is biased counterclockwise by a spring 120 and has a curved right upper edge 115 which normally is contacted by an adjustable eccentric 126 projecting forwardly from bell crank. The curved edge 115 on the latch, in conjunction with the eccentric is adapted to effectively program the position of latch 116 relative to the position of bellcrank 96.

As illustrated in FIGS. 3-4, to the movement of the carriage 78 toward the abutment 85, the bellcrank 96 is displaced counterclockwise and the eccentric 126 thereon moves along the right upper edge 115 of latch 116 limiting the action of spring 120 on the latch 116 counterclockwise until the top of the shoulder 105 passes under the car 122 and the latter comes to rest on the top of the shoulder 105 (FIG. 4). The margin counterstop member 82 then contacts the abutment 85.

As the counterstop member 82 moves into contact with the abutment 85 the carriage return clutch 44 consequently becomes opened and the carriage 78 under the control of a usual escapement mechanism drops back a little less than a letter-feed space, through the urge of the spring barrel drawband, not shown.

This dropping back of the carriage 78 to a left margin position, a distance of approximately 0.070 of an inch, allows spring 102 to pivot margin control bellcrank 96 clockwise to move the counter stop member 82 away from the limit stop 85. Clockwise movement of margin control bellcrank 96 removes the top of the shoulder 105 thereon from under the car 122 of the latch or blocking member 116, so that then under the urge of the spring 120 such blocking member will pivot counterclockwise to place its ear 122 into a relation to the shoulder 105 on the margin control bellcrank 96 which will block the latter against movement in carriage return direction as shown in FIG. 5. The blocking member 116 consequently is then severely restricting movement of the bellcrank 96 in a counterclockwise direction so as to establish an abnormal-limiting stop for the counterstop member 82, by reason of which then virtually no carriage return movement is allowed. At the time the blocking member 116 becomes pivoted counterclockwise, as stated, a cam surface 124 thereon descends on the upper edge of the portion 108 of the operating lever 110 to maintain the latter operated counterclockwise so that the end 67 of the link 66 is active on the lefthand end of the elongated slot 68 of the clutch latch member 54 to hold the latter in released position.

With the carriage now standing in left margin position, as in FIG. 5, any cyclic turn of the cam 20 which under the control of the key 2 is caused to take place, obviously will through the cam follower 24 operate the clutch control member 34 so as to hold it operated for a measured duration sufficient for the platen indexing device to become actuated and restored. There will be one such operation followed by a restoration for each cyclic turn of the cam 20 until the key 2 is released. Obviously, such manner of operation and restoration of the clutch control member 34 is made possible because the latch member 54, as shown in FIG. 5, is held in released position by the cam surface 124 bearing against the portion 108 of the operating arm 110. Moreover, while due to the operation of the key 2 the drawband 50 becomes operated repeatedly, the repetitive pull on the carriage has virtually no movement effect on the carriage because the lever 96 is blocked against movement and the margin stop 76 is engaging the counter stop 82. Whenever the key 2 is released the cam 20 will complete the started turn and the cam follower 24 will move to the normal position to force the clutch control lever 34 to the open clutch position seen in FIG. 2. Whenever thereafter the carriage is caused to move in advance direction, as for example by a first typing operation, the counter stop 82 moves correspondingly and allows the spring 102 to pivot the margin control bellcrank 96 clockwise until it is stopped by the pin 100 (see FIG. 3). In so doing, the eccentric 126 on the margin control bellcrank 96 engages the right upper edge 115 of the latch 116 and pivots the latter clockwise against the urge of the spring 120, to lift the ear 122 free of the shoulder and also to lift the cam face 124 free of the lever 110. Consequently, under the tension of the spring 111 the lever will move to the position seen in FIG. 2, and under the tension of the spring 62 the latch member 54 will bear rearwardly against the ear 58 and is ready to latch the bellcrank 34 whenever at any time thereafter the carriage return key is operated. The stated latch 116, including its ear 122 and the cam face 124 thereon, and including also the eccentric 126 on the bellcrank 96 related to it, constitute a control means, whereby when the carriage after a return advances to its initial-typing position, such control means is effective to block the carriage and counterstop 82 against significant return movement and also will cause the latch 55 for the clutch control member 54 to be held released. Conversely, whenever the carriage is caused to advance from such initial-typing position, said control means will unblock the counterstop 82 for movement in return direction and will render the latch 55 potentially effective.

I claim:

1. In a typewriter having a frame,

a carriage urged in an advance direction and being returnable,

a platen,

an operable platen-indexing device on the carriage,

a power-rotated shaft means on the frame,

a carriage return clutch,

means connectable by said carriage return clutch with said shaft means consecutively to operate said platen-indexing device and to draw the carriage in return direction,

a margin stop on the carriage for terminating carriage return movement and determining the left-hand margin position,

a carriage-return-cushioning counterstop means on the frame normally operable thereon from a normal position a given distance to a final limit stop by said margin stop through return movement of the carriage, thereby to terminate carriage return movements,

and means biasing said counterstop means to its normal position, said counterstop means and the carriage after terminating each carriage return movement, executing automatically a short movement in carriage advance direction to a left-hand margin position,

in combination therewith,

a control member for said carriage return clutch normally spring biased to an open clutch position but being positionable to close said clutch and be latched,

a latch potentially effective under spring bias to latch said control member in closed clutch position whenever it is positioned to close said clutch,

means on the frame responsive to the operation of said counterstop means in carriage return direction to said limit, to effect a releasing movement of said latch to an ineffective position and to allow the spring-biased control member to open the carriage return clutch, so that responsively the carriage and said counterstop means execute said short movement in carriage advance direction to said left-hand margin position,

control means on the frame operatively responsive to the execution of said short advance movement of the carriage to the left-hand margin position incident to the carriage return operation, to block said counterstop means and, in turn, said carriage against movement in carriage return direction, and additionally to move to hold said latch in an ineffective position for as long as the carriage remains at said left hand margin position, whereby while said carriage is in said left-hand margin position there can be effected platen-indexing operations without carriage movement, said control means being operatively responsive to advance movement of said counterstop means incident to movement of said carriage from said left-hand margin position, to unblock said counterstop means for movement again in carriage return direction, and to again render said latch potentially effective,

key means,

and means cyclically operable under the control of said key means to position said control member to closed clutch position over an interval sufficient to operate said platenindexing device.

2. The invention set forth in claim 1 wherein said control means includes a part movable into the path of said counterstop means in advance of said final limit stop.

3. The invention set forth in claim 1 wherein said control means includes a second part movable to block movement of said latch to its effective position.

4. The invention set forth in claim 1 wherein said cyclically operable means comprises a normally stationary cam on said power-rotated shaft means, a wrap spring clutch on said power-rotated shaft means, and means normally cooperative with said wrap spring clutch to cause it to be nongripping but through operation of said key means causing it to become gripping to transmit cyclic-turning movement to said cam when said key means is operated, said cam when executing a cyclic-turning movement whenever said carriage is in a position advanced from said left-hand margin position causing one operation of said indexing device followed by a carriage return movement, but while said carriage is at said left-hand margin position causing for every cyclic turning movement one operation of said indexing device without concomitant carriage movement.

5. ln a typewriter having a frame,

a carriage urged in an advance direction and being retumable,

a platen and an operable platen-indexing device on the carriage,

power-rotated shaft means on the frame,

a carriage return clutch, means connectable by said carriage return clutch with said shaft means consecutively to operate said platen-indexing device and to draw the carriage in return direction,

a carriage return margin stop on the carriage,

a carriage-retum-cushioning counterstop means on the frame operable thereon from a nonnal position a given distance to a final limit position by said margin stop through return movement of the carriage, thereby to terminate carriage return movements,

and means biasing said counterstop means to its normal position, said counterstop means and the carriage after terminating each carriage return movement, executing automatically a short movement in carriage advance direction to a left-hand margin position,

in combination therewith,

a control member for said carriage return clutch being spring biased to an open clutch position but being positionable to close said clutch,

a latch normally potentially efi'ective under spring bias to latch said control member when it is moved to closed clutch position,

means responsive to the operation of said counterstop means in carriage return direction to said final limit position, to effect release movement of said latch automatically to an ineffective position for causing the carriage return clutch to open and enable the carriage and said counterstop means to execute said short advance movement,

control means on the frame responsive to said movement of said counterstop means incident to carriage advance to said left hand margin position to block then such counterstop means against movement in carriage return direction toward its final limit position and also to hold said latch released, and being further responsive whenever a carriage advance movement next takes place, to render said latch potentially effective again and to unblock said counterstop means for movement to its final limit in carriage return direction,

normally idle cyclically operable means which if it is operated while said latch is potentially effective, will position said clutch control member to become held by said latch in closed clutch position pending the operation of said counterstop means to its final limit by return movement of the carriage, and which cyclically operable means, if it is cyclically operated repeatedly while said latch means is in an ineffective condition will repeatedly operate the clutch control member to cause each time a clutch closure of automatically limited duration,

a control key operable either to a first or to a second position,

and means responsive to the operation of said key to said first position to limit said cyclically operable means to a single operation, and responsive to the operation of said key to said second position, while said control means blocks the counterstop means and holds the latch released, to cause, until said key is released, a number of operations of said cyclically operable means for effecting a desired number of line-indexing operations.

6. The invention set forth in claim 5, wherein said cyclically operable means includes a cam member to position said clutch control member from open clutch to closed clutch position and thereafter to allow its restoration each time said latch becomes released. 

1. In a typewriter having a frame, a carriage urged in an advance direction and being returnable, a platen, an operable platen-indexing device on the carriage, a power-rotated shaft means on the frame, a carriage return clutch, means connectable by said carriage return clutch with said shaft means consecutively to operate said platen-indexing device and to draw the carriage in return direction, a margin stop on the carriage for terminating carriage return movement and determining the left-hand margin position, a carriage-return-cushioning counterstop means on the frame normally operable thereon from a normal position a given distance to a final limit stop by said margin stop through return movement of the carriage, thereby to terminate carriage return movements, and means biasing said counterstop means to its normal position, said counterstop means and the carriage after terminating each carriage return movement, executing automatically a short movement in carriage advance direction to a left-hand margin position, in combination therewith, a control member for said carriage return clutch normally spring biased to an open clutch position but being positionable to close said clutch and be latched, a latch potentially effective under spring bias to latch said control member in closed clutch position whenever it is positioned to close said clutch, means on the frame responsive to the operation of said counterstop means in carriage return direction to said limit, to effect a releasing movement of said latch to an ineffective position and to allow the spring-biased control member to open the carriage return clutch, so that responsively the carriage and said counterstop means execute said short movement in carriage advance direction to said left-hand margin position, control means on the frame operatively responsive to the execution of said short advance movement of the carriage to the left-hand margin position incident to the carriage return operation, to block said counterstop means and, in turn, said carriage against movement in carriage return direction, and additionally to move to hold said latch in an ineffective position for as long as the carriage remains at said left hand margin position, whereby while said carriage is in said lefthand margin position there can be effected platen-indexing operations without carriage movement, said control means being operatively responsive to advance movement of said counterstop means incident to movement of said carriage from said left-hand margin position, to unblock said counterstop means for movement again in carriage return direction, and to again render said latch potentially effective, key means, and means cyclically operable under the control of said key means to position said control member to closed clutch position over an interval sufficient to operate said platen-indexing device.
 2. The inventIon set forth in claim 1 wherein said control means includes a part movable into the path of said counterstop means in advance of said final limit stop.
 3. The invention set forth in claim 1 wherein said control means includes a second part movable to block movement of said latch to its effective position.
 4. The invention set forth in claim 1 wherein said cyclically operable means comprises a normally stationary cam on said power-rotated shaft means, a wrap spring clutch on said power-rotated shaft means, and means normally cooperative with said wrap spring clutch to cause it to be nongripping but through operation of said key means causing it to become gripping to transmit cyclic-turning movement to said cam when said key means is operated, said cam when executing a cyclic-turning movement whenever said carriage is in a position advanced from said left-hand margin position causing one operation of said indexing device followed by a carriage return movement, but while said carriage is at said left-hand margin position causing for every cyclic turning movement one operation of said indexing device without concomitant carriage movement.
 5. In a typewriter having a frame, a carriage urged in an advance direction and being returnable, a platen and an operable platen-indexing device on the carriage, power-rotated shaft means on the frame, a carriage return clutch, means connectable by said carriage return clutch with said shaft means consecutively to operate said platen-indexing device and to draw the carriage in return direction, a carriage return margin stop on the carriage, a carriage-return-cushioning counterstop means on the frame operable thereon from a normal position a given distance to a final limit position by said margin stop through return movement of the carriage, thereby to terminate carriage return movements, and means biasing said counterstop means to its normal position, said counterstop means and the carriage after terminating each carriage return movement, executing automatically a short movement in carriage advance direction to a left-hand margin position, in combination therewith, a control member for said carriage return clutch being spring biased to an open clutch position but being positionable to close said clutch, a latch normally potentially effective under spring bias to latch said control member when it is moved to closed clutch position, means responsive to the operation of said counterstop means in carriage return direction to said final limit position, to effect release movement of said latch automatically to an ineffective position for causing the carriage return clutch to open and enable the carriage and said counterstop means to execute said short advance movement, control means on the frame responsive to said movement of said counterstop means incident to carriage advance to said left hand margin position to block then such counterstop means against movement in carriage return direction toward its final limit position and also to hold said latch released, and being further responsive whenever a carriage advance movement next takes place, to render said latch potentially effective again and to unblock said counterstop means for movement to its final limit in carriage return direction, a normally idle cyclically operable means which if it is operated while said latch is potentially effective, will position said clutch control member to become held by said latch in closed clutch position pending the operation of said counterstop means to its final limit by return movement of the carriage, and which cyclically operable means, if it is cyclically operated repeatedly while said latch means is in an ineffective condition will repeatedly operate the clutch control member to cause each time a clutch closure of automatically limited duration, a control key operable either to a first or to a second position, and means responsive to the operation of said key to sAid first position to limit said cyclically operable means to a single operation, and responsive to the operation of said key to said second position, while said control means blocks the counterstop means and holds the latch released, to cause, until said key is released, a number of operations of said cyclically operable means for effecting a desired number of line-indexing operations.
 6. The invention set forth in claim 5, wherein said cyclically operable means includes a cam member to position said clutch control member from open clutch to closed clutch position and thereafter to allow its restoration each time said latch becomes released. 